The present invention relates to a hot water distribution system in general, and more particularly to a system providing an almost instantaneous supply of hot water on demand.
One of the problems associated with hot water distribution systems of conventional design is that associated with the requirement of drawing water, for example from a hot water faucet, for a relatively long period of time prior to obtaining at the faucet outlet water at the desired temperature. This is due to the fact that the water heater and hot water tank, generally combined in a single unit, may be located at a considerable distance from a hot water faucet or to an apparatus utilizing hot water such as, for example, a clothes washer, a dish washer or the like. Attempts have been made in the past to insulate hot water conduits and pipes from the ambient by wrapping the pipes and conduits with a heat insulation material. Nevertheless, more particularly when there is only an occasional demand for hot water, the conduits and pipes and the stagnant water in the conduits and pipes rapidly cool to a temperature close to ambient temperature. When there is a sudden demand for hot water, wasted water must be allowed to flow from the faucet until the colder water in the supply pipe is exhausted. When the momentary demand for hot water is from a hot water usage apparatus, such as a clothes washer or dishwasher permanently connected to the hot water supply, the stagnant water in the supply pipe may be a temperature too low to accomplish the desired results in the most efficient manner. Hot water faucets, which require that they be open long enough to purge from the supply conduits or pipes the residual water having cooled down to ambient temperature, lead to excessive loss of water and to an increase in the cost of the energy required for maintaining the water at a required temperature in the water heater hot water tank.
The disadvantages of conventional hot water supply systems for dwelling houses, apartment buildings, offices, manufacturing plants are more particularly important in the northern latitudes where ambient temperatures may drop far below freezing during the winter, where long conduits or pipes are used from a centrally located hot water tank to various remote locations of the building. The heat losses may be such that it is not uncommon for hot water pipes to freeze.